docs: def interface_to_relations(interface_name):
      """
      Given an interface, return a list of relation names for the current
      charm that use that interface.
  
      :returns: A list of relation names.
      """
      results = []
      for role in ('provides', 'requires', 'peers'):
          results.extend(role_and_interface_to_relations(role, interface_name))
      return results